An oil overflow valve for a self-controlled bypass diaphragm compressor

Abstract

This application discloses a self-controlled bypass diaphragm compressor overflow valve, relating to the field of diaphragm compressor technology. It not only enables overflow valve bypass during the start-up phase, facilitating light-load start-up and fully automatic control of the compressor, but also allows for the responsive adjustment of overflow pressure and discharge pressure. The overflow valve includes a valve cover, a valve body, and a valve seat; an isolation chamber with an internal spring is formed between the valve cover and the valve body; a valve stem cavity is confined within the valve seat; a high-pressure oil channel and an overflow channel are provided on the wall of the valve stem cavity; the valve head of the valve stem seals against the outlet of the high-pressure oil channel, and the valve tail extends out of the valve stem extension hole and abuts against the lower end of the spring; an overflow cavity is formed between the valve head and the valve seat; the inlet of the high-pressure oil channel connects to the oil chamber of the diaphragm compressor; the diameter of the sealing section is larger than the diameter of the valve head of the valve stem; the sealing section divides the valve stem cavity into a gas chamber and an overflow cavity; an annular protrusion divides the gas chamber into a first gas chamber and a second gas chamber connected to the compressed air source. This application aims to improve the performance of the overflow valve.

Description

Technical Field

[0001] This application relates to the field of diaphragm compressor technology, and in particular to an oil overflow valve for a self-controlled bypass diaphragm compressor. Background Technology

[0002] Diaphragm compressors are a type of positive displacement compressor. Due to their good sealing performance, wide pressure range, and large compression ratio, they are widely used in petrochemical fields such as hydrogen refueling stations to compress and transport various high-purity gases, precious rare gases, toxic and harmful gases, and corrosive gases.

[0003] Because diaphragm compressors use a piston to drive hydraulic oil to compress the working fluid, hydraulic oil inevitably leaks from the piston during operation. Therefore, diaphragm compressors are usually equipped with a replenishment line to supply oil to the oil chamber. However, since the replenishment amount is rarely exactly the same as the leakage amount, it is generally slightly larger. Therefore, for any working stroke of the diaphragm compressor, the amount of oil in the oil chamber will be slightly larger after replenishment. When the diaphragm contacts the upper stop plate, the piston is still driving the hydraulic oil to compress. Because oil has relatively low compressibility, the oil pressure will suddenly increase. Therefore, an overflow valve is also required in the oil chamber to allow excess oil to overflow and control the oil pressure.

[0004] Meanwhile, when the diaphragm compressor is shut down for an extended period, a significant amount of oil leakage and air accumulation will occur in the oil chamber. Directly starting the compressor under these conditions would cause air to mix into the oil, negatively impacting system stability. Therefore, an overflow bypass passage needs to be added to the diaphragm compressor oil chamber to purge air from the chamber before startup, ensuring that the compressor is not under oil pressure load during startup.

[0005] In addition, the overflow pressure of some diaphragm compressors used for changes in discharge pressure needs to be adjusted according to the changes in discharge pressure, which requires the overflow pressure of the overflow valve to be adjustable with the discharge pressure. Summary of the Invention

[0006] To address the aforementioned technical problems, embodiments of this application provide a self-controlled bypass diaphragm compressor overflow valve, which not only enables overflow valve bypass during the startup phase, facilitating light-load startup and fully automatic control of the compressor, but also allows for the responsive adjustment of overflow pressure and discharge pressure.

[0007] To achieve the above objectives, embodiments of this application provide a self-controlled bypass diaphragm compressor overflow valve, comprising a valve cover, a valve body, and a valve seat connected in series from top to bottom; an isolation cavity is formed between the lower end of the valve cover and the upper end of the valve body; a spring is provided within the isolation cavity; a valve stem extension hole is provided at the lower end of the valve body; a stepped valve stem cavity is restricted within the valve seat; a high-pressure oil passage is provided on the bottom wall of the valve stem cavity, and an overflow passage is provided on the side wall of the valve stem cavity; a valve stem is provided within the valve stem cavity; the valve stem includes a valve head, a sealing section, an annular protrusion, and a valve tail arranged in series from bottom to top; the valve head of the valve stem seals against the high-pressure oil passage. At the outlet of the channel, the valve tail of the valve stem extends out of the valve stem extension hole and abuts against the lower end of the spring; an overflow cavity is formed between the valve head end of the valve stem and the valve seat; the overflow channel communicates with the overflow cavity; the inlet of the high-pressure oil channel is used to communicate with the oil chamber of the diaphragm compressor; when the valve stem retracts, the outlet of the high-pressure oil channel communicates with the overflow cavity; the diameter of the sealing section is larger than the diameter of the valve head of the valve stem; the sealing section divides the valve stem cavity into an air chamber and the overflow cavity; the annular protrusion divides the air chamber into a first air chamber and a second air chamber, both of which are connected to the compressed air source.

[0008] Furthermore, the upper end of the valve cover is provided with a high-pressure air chamber; one end of the high-pressure air chamber is slidably connected to an air piston, and the other end is used to connect to the exhaust pipe of the diaphragm compressor.

[0009] Furthermore, the flow area of ​​the high-pressure air chamber is 1.1 to 1.2 times that of the flow area of ​​the high-pressure oil channel.

[0010] Furthermore, a lower spring seat is provided inside the isolation chamber; the gas piston includes a piston portion and an upper spring seat portion disposed at the lower end of the piston portion; the piston portion is located inside the high-pressure gas chamber, and the upper spring seat portion is located inside the isolation chamber; the two ends of the spring abut against the upper spring seat portion and the lower spring seat respectively; the valve tail of the valve stem extends out of the valve stem extension hole and abuts against the lower end of the lower spring seat.

[0011] Furthermore, the isolation chamber is provided with a protective gas inlet and a vent outlet on its side wall. The protective gas inlet is connected to an external nitrogen source, and the vent outlet is connected to a vent pipe.

[0012] Furthermore, the valve body is connected to the valve cover and the valve seat by threads.

[0013] Furthermore, a first sealing element is provided between the orifice wall of the high-pressure gas chamber and the gas piston; a second sealing element is provided between the orifice wall of the valve stem protrusion and the valve tail end of the valve stem; a third sealing element is provided between the side wall of the valve stem cavity and the sealing section; and a fourth sealing element is provided between the side wall of the valve stem cavity and the annular protrusion; the first sealing element, the second sealing element, the third sealing element, and the fourth sealing element are all piston ring type sealing elements or packing type sealing elements.

[0014] This application has the following advantages over the prior art:

[0015] 1. In this embodiment, a valve stem is used to divide the valve stem cavity into a first gas chamber, a second gas chamber, and an overflow chamber. The first and second gas chambers are connected to the compressed air source, and the overflow chamber is connected to the oil chamber of the diaphragm compressor. A spring is installed in the isolation chamber formed between the valve cover and the valve body to prevent the valve stem from moving away from the valve seat. Thus, during the compressor start-up phase, since the compressor's discharge pressure is zero, after compressed gas is introduced into the first gas chamber, the gas pressure can lift the valve stem, causing the valve head of the valve stem to separate from the valve seat. The high-pressure oil passage is connected to the overflow chamber, and the overflow valve is in a bypass state. The oil pressure in the oil chamber is at atmospheric pressure. At this time, the compressor starts without load and can smoothly discharge air bubbles in the oil chamber. After the compressor starts, the gas pressure in the first chamber is released, and compressed gas is introduced into the second chamber. The gas in the second chamber exerts a downward force on the valve stem, so that the oil pressure has a certain initial load to ensure that the compressor can enter the working state normally. In this way, the overflow valve can be bypassed during the start-up stage, which is beneficial for the light-load start-up of the compressor, and this bypass operation can be automatically controlled.

[0016] 2. In this embodiment, a high-pressure air chamber is provided at the upper end of the valve cover. One end of the high-pressure air chamber is connected to the exhaust pipe of the compressor, and the other end is slidably connected to the air piston. The valve cover integrates the functions of the valve cover and the cylinder, and the air piston integrates the functions of the piston and the spring seat. Thus, the pressure of the spring acting on the valve stem can be automatically adjusted according to the pressure of the compressor's exhaust pipe, thereby realizing the follow-up of the overflow pressure and the exhaust pressure.

[0017] 3. In this embodiment of the application, by setting a first air chamber, a second air chamber and an isolation chamber between the overflow chamber and the high-pressure air chamber, multiple mutually isolated chambers are formed between the exhaust gas and the oil, ensuring that the hydraulic oil will not contaminate the compressed gas.

[0018] 4. The embodiments of this application provide protection against leakage of flammable and explosive gases by filling the isolation chamber with protective gas. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the oil overflow valve of the self-controlled bypass diaphragm compressor in an embodiment of this application. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation", "connection" and "joining" should be interpreted broadly, for example, as fixed connection, detachable connection, or integral connection; those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0025] Reference Figure 1 This application provides an oil overflow valve for a self-controlled bypass diaphragm compressor, including a valve cover 1, a valve body 2, a valve seat 3, and a valve stem 4. The lower end of the valve cover 1 is connected in series with the valve body 2 and the valve seat 3.

[0026] The upper end of the valve cover 1 is provided with a high-pressure air chamber a. The lower end of the valve cover 1 is connected to the upper end of the valve body 2 by a thread, and an isolation chamber b is formed between the two. The high-pressure air chamber a and the isolation chamber b are connected. The upper end of the high-pressure air chamber a is connected to the exhaust pipe of the diaphragm compressor, and the lower end of the high-pressure air chamber a is slidably connected to the air piston 5.

[0027] The piston 5 includes a piston portion 51 and an upper spring seat portion 52 disposed at the lower end of the piston portion 51. The piston portion 51 is located within a high-pressure air chamber a and can reciprocate along the axial direction of the high-pressure air chamber a. The upper spring seat portion 52 is located within an isolation chamber b. A first seal 10 is provided between the piston portion 51 and the side wall of the high-pressure air chamber a. The first seal 10 can separate the high-pressure air chamber a and the isolation chamber b. The first seal 10 can be a piston ring seal or a packing seal.

[0028] The isolation chamber b is equipped with a spring 6 and a lower spring seat 7, with the two ends of the spring 6 abutting against the upper spring seat portion 52 and the lower spring seat 7, respectively. The side wall of the isolation chamber b is provided with a protective gas inlet b1 and a vent port b2. Specifically, both the protective gas inlet b1 and the vent port b2 are located on the valve body 2, with the protective gas inlet b1 connected to an external nitrogen source and the vent port b2 connected to a vent pipe.

[0029] For diaphragm compressors with high discharge pressure, the first seal 10 cannot guarantee complete leak-free operation, and a small amount of gas may leak into the isolation chamber b. When the compressed medium is a flammable or explosive gas, a protective gas, such as nitrogen, is introduced into the isolation chamber b through the protective gas inlet b1. The vent port b2 is connected to the vent pipe, allowing the leaked gas to be discharged into the vent pipe.

[0030] The valve body 2 and valve seat 3 are also connected by threads. The lower end of the valve body 2 has a valve stem extension hole 21. A stepped valve stem cavity c is defined within the valve seat 3. A high-pressure oil passage c1 is provided on the bottom wall of the valve stem cavity c, and the valve stem 4 is located within the valve stem cavity c. The flow area of ​​the high-pressure air cavity a is 1.1 to 1.2 times the flow area of ​​the high-pressure oil passage c1.

[0031] The valve stem 4 includes, from bottom to top, a valve head 41, a sealing section 42, an annular protrusion 43, and a valve tail 44. The valve head 41 of the valve stem 4 seals against the outlet of the high-pressure oil passage c1, and the valve tail 44 of the valve stem 4 extends out of the valve stem extension hole 21 and abuts against the lower end of the lower spring seat 7. A second sealing element 11 is provided between the wall of the valve stem extension hole 21 and the valve tail 44 of the valve stem 4. The second sealing element 11 can separate the gas chamber and the isolation chamber b. An overflow chamber d is formed between the valve head end of the valve stem 4 and the valve seat 3, and an overflow channel d1 is provided on the side wall of the overflow chamber d.

[0032] The diameter of the sealing section 42 is larger than the diameter of the valve head 41 of the valve stem 4. A third sealing element 12 is provided between the side wall of the valve stem cavity c and the sealing section 42, dividing the valve stem cavity c into an air cavity and the aforementioned overflow cavity d. A fourth sealing element 13 is provided between the side wall of the valve stem cavity c and the annular protrusion 43. The fourth sealing element 13 divides the air cavity into a first air cavity e and a second air cavity f, and both the first air cavity e and the second air cavity f are connected to a compressed gas source. Specifically, a first compressed gas channel e1 is provided on the side wall of the first air cavity e, and a second compressed gas channel f1 is provided on the side wall of the second air cavity f. Compressed gas can be introduced into or released into the first air cavity e and the second air cavity f respectively through the first compressed gas channel e1 and the second compressed gas channel f1.

[0033] The second seal 11, the third seal 12, and the fourth seal 13 are all piston ring seals or packing seals.

[0034] The working principle of this application embodiment is as follows:

[0035] During the compressor start-up phase, the compressor's discharge pressure is zero, and compressed gas is introduced into the first gas chamber e. The area of ​​the gas in the first gas chamber e acting on the valve stem 4 is denoted as A. c The air pressure in the first air chamber e is denoted as P. c And the air pressure satisfies P c A c The force is greater than the weight and friction of valve stem 4. When compressed gas is introduced into the first gas chamber e, the gas pressure can lift valve stem 4, causing the valve head sealing surface of valve stem 4 to separate from valve seat 3. The high-pressure oil passage c1 is connected to the overflow chamber d, the overflow valve is in bypass state, and the oil pressure in the oil chamber is at normal pressure, so that the compressor starts without load and can smoothly discharge air bubbles in the oil chamber.

[0036] After the compressor starts, the gas pressure in the first gas chamber e is released, and compressed gas is introduced into the second gas chamber f. The gas in the second gas chamber f exerts a downward force on the valve stem 4, giving the oil pressure a certain initial load to ensure that the compressor can enter the working state normally.

[0037] Additionally, since the inlet of high-pressure oil passage c1 is connected to the oil chamber of the diaphragm compressor, when the oil pressure in the oil chamber is higher than a preset value, the high-pressure oil in high-pressure oil passage a can lift the valve stem 4, and the outlet of high-pressure oil passage c1 is connected to the overflow chamber d. The high-pressure oil will overflow into the overflow chamber d and be discharged through the overflow passage d1.

[0038] Since the compressor exhaust pipe is connected to the high-pressure chamber a, the pressure in the high-pressure chamber a is equal to the compressor exhaust pressure. This exhaust pressure acts on the piston 5 and is transmitted to the valve stem 4 via the spring 6. Therefore, for the oil pressure to open the valve stem 4, it needs to overcome the force of the exhaust pressure. For ease of description, the flow area of ​​the high-pressure chamber a is denoted as A. 气 Air pressure is denoted as P. 气 The flow area of ​​the high-pressure oil passage a, that is, the area where the oil pressure acts on the valve stem 4, is denoted as A. 油 ,but:

[0039] P 油 ·A 油 =P 气 ·A 气

[0040] Oil overflow pressure P 油 It can be represented as:

[0041]

[0042] To ensure stable operation of the diaphragm compressor, the oil overflow pressure generally needs to be set to 1.1-1.2 times the discharge pressure. In this embodiment, the flow area A of the high-pressure gas chamber a is... 气 The area A designed for the hydraulic pressure acting on valve stem 4 is... 油 It is 1.1 to 1.2 times that of the compressor. Therefore, the oil overflow pressure can be automatically adjusted to match the discharge pressure, regardless of whether the compressor discharge pressure is stable or changing.

[0043] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A self-acting bypass diaphragm compressor spill valve characterized by, The valve cover, the valve body and the valve seat are sequentially connected from top to bottom; The lower end of the valve cover and the upper end of the valve body form an isolation cavity; the isolation cavity is provided with a spring; The lower end of the valve body is provided with a valve rod extension hole; the valve seat is limited to a stepped valve rod cavity; the bottom wall of the valve rod cavity is provided with a high-pressure oil passage, and the side wall of the valve rod cavity is provided with an overflow passage; the valve rod cavity is provided with a valve rod; The valve rod comprises a valve head, a sealing section, an annular protrusion and a valve tail which are sequentially arranged from bottom to top; the valve head of the valve rod seals against the outlet of the high-pressure oil passage, and the valve tail of the valve rod abuts against the lower end of the spring after extending out of the valve rod extension hole; the valve head end of the valve rod and the valve seat form an overflow cavity; the overflow passage communicates with the overflow cavity; the inlet of the high-pressure oil passage is used to communicate with the oil cavity of the diaphragm compressor; when the valve rod is retracted, the outlet of the high-pressure oil passage communicates with the overflow cavity; The diameter of the sealing section is greater than the diameter of the valve head of the valve rod; the sealing section separates the valve rod cavity into a gas cavity and the overflow cavity; the annular protrusion separates the gas cavity into a first gas cavity and a second gas cavity, and the first gas cavity and the second gas cavity both communicate with a compressed gas source.

2. The self-piloted bypass diaphragm compressor spill valve of claim 1, wherein, The upper end of the valve cover is also provided with a high-pressure gas cavity; one end of the high-pressure gas cavity is slidably connected with a gas piston, and the other end is used to communicate with the exhaust pipeline of the diaphragm compressor.

3. The self-piloted bypass diaphragm compressor spill valve of claim 2, wherein, The flow area of the high-pressure gas cavity is 1.1-1.2 times the flow area of the high-pressure oil passage.

4. The self-piloted bypass diaphragm compressor spill valve of claim 2, wherein, The isolation cavity is also provided with a lower spring seat; the gas piston comprises a piston part and an upper spring seat part arranged at the lower end of the piston part; the piston part is located in the high-pressure gas cavity, and the upper spring seat part is located in the isolation cavity; the two ends of the spring abut against the upper spring seat part and the lower spring seat respectively; the valve tail of the valve rod abuts against the lower end of the lower spring seat after extending out of the valve rod extension hole.

5. The self-piloted bypass diaphragm compressor spill valve of claim 1, wherein, The side wall of the isolation cavity is provided with a protective gas inlet and a vent; the protective gas inlet communicates with an external nitrogen source; the vent communicates with a vent pipe.

6. The self-piloted bypass diaphragm compressor spill valve of claim 1, wherein, The valve body, the valve cover and the valve seat are all connected by threads.

7. The self-piloted bypass diaphragm compressor spill valve of claim 2, wherein, First, second, third and fourth sealing elements are arranged between the hole wall of the high-pressure gas cavity and the gas piston, between the hole wall of the valve rod extension hole and the valve tail end of the valve rod, between the side wall of the valve rod cavity and the sealing section, and between the side wall of the valve rod cavity and the annular protrusion; the first, second, third and fourth sealing elements are all piston ring type sealing elements or packing type sealing elements.

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